On a 67 all the side trim and rear trim is different including the tail light bezels.
The 67 plain 300 has no trim side or rear.
66 deluxe had body side molding midway, no rockers nor wheel opening and 300 deluxe emblems, no roof rail.
66 300 had no trim at all.
Interior trim level was different also on 66 and 67 300 deluxe and 300